This disclosure relates to equipment having reaction vessels used to manufacture chemical and/or biological products such as biopharmaceuticals. For instance, fermentors commonly provide a reaction vessel for cultivation of microbial organisms or mammalian, insect, or plant cells to produce such products. It is important to control the temperature of the reaction to ensure optimal production of the product. For example, fermentations typically produce excess heat that must be dissipated or removed from the system to ensure proper reaction conditions. Those of skill in the art have suggested various systems for controlling the temperature within reaction vessels, as briefly reviewed below. However, there remains a need in the art for improved heat control systems that also incorporates the use of sanitary material surfaces, such as that provided herein.
Previously available systems are described in several U.S. and foreign patents. For instance, U.S. Pat. No. 2,973,944 (Etter, et al.) describes a system of “individual coil units” that each contain a group of tubes that serve as heat transfer elements in a reaction vessel. The units are indirectly affixed to the inner part of the vessel using bracing members located at the top, bottom, and/or throughout the length of each unit. The '944 patent points out that an advantage of such indirect attachment is that the expansion and contraction units during will not damage the reactor shell. The units described by the '944 patent are not internal, e.g., part of a baffle, but instead consist of multiple tubes fully exposed to the reaction vessel. Another tube-based system is described in U.S. Pat. No. 3,986,934 (Muller, H.) which provides a baffle including multiple tubes, the baffle being positioned substantially in the center of the reaction vessel. The fermentation media is circulated through the baffle such that is contacts the tubes containing the heat transfer media to optimize contact between the reaction components and the heat transfer media. And U.S. Pat. No. 4,670,397 (Wegner, et al.) discloses a system of tube baffles spaced approximately evenly around the fermentor circumference. The baffles that are positioned apart from the fermentor wall, thereby providing a space between the outer shell of the fermentor and the baffles.
U.S. Pat. No. 4,985,208 (Sugawara, et al.) illustrates a polymerization reaction apparatus including multiple heat transfer elements attached to the inner wall of the reaction vessel between agitating blades. Heat transfer medium may be circulated within an internal passage of the heat transfer elements. The internal passage may be formed in a “zigzag” pattern provided using alternately disposed reinforcing plates. Similarly, U.S. Pat. No. 4,460,278 (Tetsuyuki, et al.) discloses a cylindrical vessel with heat exchangers installed between agitating blades.
Commercially available systems currently offered by manufacturers (e.g., Tranter, Paul Mueller, Omega) include platecoils, spiral-wound pipe systems, and other vertical pipe loop systems. For instance, the Platecoil® system provides heat transfer elements constructed from two metal sheets that are resistance welded together to form passages through which heat transfer media is circulated. Platecoils are available in various forms and are suitable for insertion within a reaction vessel.
The currently available systems do not provide both sufficient structural integrity for use in high power-per-volume reactors and sanitary construction. The heat transfer systems described herein include a baffle described that solves these problems. As described below, the baffle typically has distribution channels through which heat transfer media is circulated and one or more relief channels through which heat transfer media is not circulated, which may also function as a vent for the distribution channels. This construction provides exceptional structural integrity. The baffle is also typically affixed to the reaction vessel such that substantially no seams appear between the baffle and the vessel, thereby providing a surface suitable to sanitization.